Magnetic resonance imaging (MRI) is an imaging scan method that magnetically excites nuclear spins of a subject placed in a magnetostatic field by a radio frequency (RF) pulse having a Larmor frequency thereof, to generate an image from magnetic resonance signal data generated with the excitation.
Several patients that are candidates for MRI have varying metal elements implanted within their bodies. These metal elements can be of many different types, including staples and other surgical implements, dental elements such as crowns and fillings, fixation devices such as plates, screws and pins, artificial joints, including hip implants and artificial knees, and pacemakers and other implantable electrical devices. Typically a metal artifact consists of an area of zero signal in an MRI, often with a high intensity rim on one or two edges, with neighboring regions showing a marked distortion. These distortion and signal problems are due to most metals having higher susceptibilities to magnetization than the body tissues they are surrounded by, thereby creating large magnetic field inhomogeneities around the metal object.
Typical methods for adjusting for metal elements can increase scan times or not resolve the signal and distortion issues caused by that metal elements.
An object of the present disclosure is to provide a magnetic resonance imaging apparatus and a magnetic resonance imaging method that can scan a region of a patient that includes a metal element with less distortion.